1. Field of the Invention
This invention relates to internal combustion engines and, more particularly, relates to a method and apparatus for utilizing both gaseous and liquid fuel in an internal combustion engine to increase fuel economy and engine efficiency while at the same time maintaining low levels of undesirable exhaust emissions.
2. Description of the Prior Art
As gasoline supplies become more scarce and costly and the need for fuel conservation becomes more readily apparent, alternate sources of fuels and methods of fuel conservation become more attractive, particularly for internal combustion engines for automotive use. Proposals for fuels other than gasoline for such engines have been made but use of alternate fuels require expensive modifications in internal combustion engine technology which are not practical to implement.
The present invention provides a method and apparatus which may be readily adapted to existing internal combustion engines and which provides a significant saving in gasoline consumption and lower cost during operation than that which can be attained using gasoline alone. The present invention uses a system which allows the burning of a gaseous fuel along with gasoline in internal combustion engines. Gaseous fuels which may be utilized with the present invention are such gaseous fuels as propane, natural gas, coal gas, butane, ethane, methane, water gas, producers gas, marsh gas, hydrogen or any other combustible gas. Many of these gases are available today or can become readily available in the near future as the technology for producing these gaseous fuels in high volume is already established. All of these gases can be compressed and stored and can be made readily available for efficient and effective distribution for automotive use.
A number of systems have been proposed for utilizing gaseous and liquid fuels in automotive engines but such prior proposed devices have involved more than a simple modification to a standard internal combustion engine or the use of complex manual controls. One device disclosed in U.S. Pat. No. 4,068,639 suggests the use of a gaseous fuel such as propane but requires use of a separate gaseous fuel reservoir and manual controls. Another prior art device, shown in U.S. Pat. No. 3,753,424, injects a gaseous fuel only at load conditions of the engine but this device is operable only with a fuel injection device and not with the standard carburetor most prevalent in internal combustion engines. A still further prior art device is that shown in U.S. Pat. No. 3,718,000 which teaches using a dual system to enable the operator of the vehicle to switch from either liquid fuel to gaseous fuel. This system does not teach or suggest use of both gaseous and liquid fuels at the same time. A similar system is also shown in U.S. Pat. Nos. 2,381,304 and 3,659,574. Another prior art system is shown in U.S. Pat. No. 2,339,988 which provides two carburetors, one for liquid fuel and the other for gaseous fuel. It has also been long known in the art that an internal combustion engine can run on a gaseous fuel such as propane alone and such a propane fuel engine is shown in U.S. Pat. No. 2,675,793.
None of these prior art devices use the system of the present invention wherein both gaseous and liquid fuels are used at the same time in an internal combustion engine which needs to be modified only slightly to incorporate the system of the present invention.